Inorganic Problem

1. The addition of PR3 to NiBr2 at 78° C in CS2 gives a red complex with the formula Ni(PR3)2Br2, which is converted to a green complex of the same formula on standing at room temperature. The red complex is diamagnetic, but the green complex is paramagnetic ( = 3.2 Bohr Magnetons).

a. Using crystal field theory, draw the d -orbital energy diagram for a square planar complex and a tetrahedral complex. Label each diagram with the appropriate complex and d orbitals.

b. Using the character table, assign the appropriate symmetry labels to each orbital(s).

c. Which of these complexes is square planar and which is tetrahedral? Put the electrons into each of these diagrams. Use the magnetism of the complexes to explain your choice.

d. For which compound would you expect to find structural isomers? What are the labels for these isomers?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2. Consider the polyatomic molecule [ZnH4]2, which has a tetrahedralgeometry.Construct an MO diagram using the following steps.

a. Determine the symmetries and degeneracies of the valence s, px, py, pz, dz2, dx2 – y2, dxy, dyz, dzx orbitals on the central iridium atom. Label the orbitals on the metal side of the MO diagram accordingly.

b. Draw the symmetry adapted orbitals (SAO’s) of 1 s orbitals for the four terminal H atoms and label these both here and in the MO diagram.

c. Construct the MO Energy diagram for [ZnH4]2. Be sure to connect the Zn and H Atomic Orbitals (AO’s) to the central MO’s so that all of the AO’s that contribute to each MO are connected to it. Clearly label each MO with the appropriate symmetry label and number.

d. Clearly label each MO as bonding, nonbonding, and antibonding.

e. Place the electrons into the diagram—AO’s and MO’s.

f. Calculate the bond order for the entire molecule and for each Zn—H bond.

MO diagram for [ZnH4]2.

 

 

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